This joint staff report on Big Oil’s decades-long deception campaign is the culmination of a nearly three year-long investigation by the Democratic staff of the House Committee on Oversight and Accountability (House Oversight), which has worked with Democratic staff of the Senate Budget Committee staff during the 118th Congress. The investigation, focused on ExxonMobil Corporation (Exxon), Chevron Corporation (Chevron), Shell USA Inc. (Shell), BP America Inc. (BP), the American Petroleum Institute (AI), and the Chamber of Commerce (the Chamber), provides a rare glimpse into the extensive efforts undertaken by fossil fuel companies to deceive the public and investors about their knowledge of the effects of their products on climate change and to undermine efforts to curb greenhouse gas emissions.